Microwave-cyclotron-resonance plasma thruster and associated operating method, and use

Abstract

The invention relates to a microwave-cyclotron-resonance plasma thruster comprising a permanent-magnet stack, a coaxial electrode array, an anode and a cathode, wherein: the permanent-magnet stack comprises at least one permanent magnet, the at least one permanent magnet being annular and having a magnetisation in the axial direction; the coaxial electrode array has an inner coaxial conductor and an outer coaxial conductor; and the thruster is semiconductor-based and cylindrical, the inner cross-sectional surface area being circular or elliptical or circular-like. The invention also relates to an operating method for operating a microwave-cyclotron-resonance plasma thruster according to the invention. The invention also relates to a use.

Description

[0001] MICROWAVE CYCLOTRON RESONANCE PLASMA THROTTLE AND ASSOCIATED

[0002] OPERATING PROCEDURES AND USE

[0003] A microwave cyclotron resonance plasma thruster comprising a permanent magnet stack, a coaxial electrode assembly, an anode, and a cathode, wherein the permanent magnet stack comprises at least one permanent magnet, the at least one permanent magnet being annular and having a magnetization in the axial direction; the coaxial electrode assembly comprising an inner coaxial conductor and an outer coaxial conductor, the thruster being semiconductor-based and cylindrical, the inner cross-sectional area being circular or elliptical or circular-like.

[0004] The invention further relates to an operating method for operating a microwave cyclotron resonance plasma thruster according to the invention. The invention also relates to a use.

[0005] Today, the use of small transmitters and receivers in the microwave frequency range is suitable for mass production in telecommunications. Microwave sources enable robust plasma generation. Such microwave-generated plasmas are used in a variety of ways in plasma processing technology. Typical applications include etching and coating solid surfaces, exhaust gas purification, and medical applications. In recent years, miniaturized atmospheric-pressure microwave plasma sources have increasingly entered the market, allowing for relatively simple handling.

[0006] Microwave technology, in particular, has experienced rapid development in recent decades. While previously only klystrons, magnetrons, and traveling-wave tubes were used to generate microwaves, it is becoming apparent that these will be replaced by semiconductor technology in the future, even at higher power levels.

[0007] For example, plasma jets for atmospheric pressure conditions are now also being marketed with semiconductor-based GHz electronics that generate the microwaves.

[0008] Plasma sources that generate plasmas using microwave frequencies are currently used commercially primarily for material processing purposes.

[0009] The Japanese Hayabusa mission, in which traveling-wave tubes were used to generate microwaves for gridded ion thrusters, is well known from the state of the art. The microwaves were used for both the main plasma and the smaller plasma of the neutralizer, which represents a useful option for generating microwave plasma. However, the following publications concerning vacuum-capable plasma-utilizing thrusters designed for use in space, for example, are particularly common.

[0010] State-of-the-art HEMP thrusters feature a stack of permanent magnet rings arranged with opposite magnetic polarity between adjacent magnets. The resulting static magnetic field is weak along the symmetry axis and also has field-free points, while possessing a strong radial field component toward the magnets. The electric field is essentially axially oriented and serves both to generate plasma and accelerate ions. The arrangement of strong, oppositely polarized magnets in close proximity requires considerable forces and secure locking.

[0011] The document CN 104234957 A discloses a device for ensuring this locking of the oppositely polarized strong magnets in a HEMP engine.

[0012] Furthermore, the document CN 113309680 A describes that permanent magnets are limited in terms of the magnetic fields they can achieve, which also limits the efficiency of plasma generation and thrust. The document CN 113309680 A discloses a magnetic field generation method using two coils arranged one inside the other, which generate opposing magnetic fields.

[0013] Radially directed magnetic field components form between the widely spaced coil windings.

[0014] From the documents CN 109681398 A and US 7,493,869 B1, plasma generation using the electron cyclotron resonance effect (ECR effect) and permanent magnets is also known.

[0015] The document US 7,493,869 B1 discloses the generation of a relatively large, dense and uniform plasma with subsequent guidance onto a workpiece in order to improve material processing.

[0016] In "Development of Microwave Discharge Engine System for Asteroid Sample and Return Mission MUSES-C", The Journal of Space Technology and Science, 1997, Volume 13, Issue 1, Pages 1_26-1_34, Funaki, Kuninaka et al. describe a 1 kW class ion thruster system for the collection and return of asteroid samples. The designed thruster has a secondary microwave discharge that does not cause degradation of a thermionic cathode as used in conventional ion thrusters, thus enabling the very long lifetime required for the sample collection and return mission. In the ion thruster head, microwave power is converted from a coaxial line into a circular cross-section waveguide and fed into the main discharge chamber, which has circularly arranged magnets or ring magnets.The electron cyclotron resonance layer, where most of the plasma generation is expected to take place, lies above the magnets, from which the generated ions diffuse and are then drawn off by an accelerating grid. As for the microwave neutralizer, the microwaves are introduced into the discharge chamber via an L-shaped antenna.

[0017] Furthermore, in "Status of Microwave Discharge Ion Engines on Hayabusa Spacecraft," AIAA 2007-5196, 43rd AIAA / ASME / SAE / ASEE Joint Propulsion Conference & Exhibit, Kuninaka, Nishiyama, et al., disclose cathodeless electron cyclotron resonance ion engines deployed in a spacecraft. These engines have the following technological features:

[0018] - Xenon ions are generated by electron cyclotron resonance microwave discharge;

[0019] - Neutralizers are operated by electron cyclotron resonance microwave discharge;

[0020] - a single microwave generator feeds the ion generator and the neutralizer simultaneously;

[0021] - 3 DC power supplies for ion acceleration;

[0022] - the electrostatic grid system is made of a carbon-carbon composite with a stable distance between the grids.

[0023] In particular, the publication CN 109681398 A describes an engine for space propulsion with the most efficient plasma generation possible, for which purpose various ionization zones are provided through which the neutral gas flows. The engine's design is complex.

[0024] The main problems with the current state of the art are that existing electron cyclotron resonance (ECR) thrusters do not use semiconductor generators and, in addition, require a grid system consisting of at least three grids. The use of grid systems is complex and, moreover, they can be eroded.

[0025] The realization of the electron cyclotron resonance effect (ECR effect) using permanent magnets is known from the literature. However, so far, only complex arrangements for use in space engines, i.e., under vacuum, as described in publication CN 109681398 A, are known.

[0026] The present invention is based on the object of providing an engine in which a plasma can be generated in a vacuum environment using microwaves simply and without a complex system design. The plasma generation using microwaves is to be carried out using semiconductor technology.

[0027] This object is achieved with a microwave cyclotron resonance plasma thruster according to the main claim and a method for operating the microwave cyclotron resonance plasma thruster according to the independent claim. Microwave cyclotron resonance plasma thruster comprising a permanent magnet stack, a coaxial electrode arrangement, an anode and a cathode, wherein

[0028] - the permanent magnet stack comprises at least one permanent magnet, wherein the at least one permanent magnet is ring-shaped and has a magnetization in the axial direction;

[0029] - the coaxial electrode arrangement comprises an inner coaxial conductor and an outer coaxial conductor;

[0030] - the engine is semiconductor-based and cylindrical, wherein the inner cross-sectional area is circular or elliptical or similar to a circle (e.g. square or polygonal or the like); and wherein the engine is characterized in that

[0031] - the permanent magnet stack is arranged spatially in length beyond the coaxial electrode arrangement;

[0032] - the inner coaxial conductor protrudes beyond the outer coaxial conductor in a defined length interval [zc1, zc2];

[0033] - the cathode has a high degree of transparency;

[0034] - the anode does not extend spatially into the coaxial conductor and is arranged downstream of the coaxial conductor in the direction of flow;

[0035] - the permanent magnets all have the same magnetization in the axial direction;

[0036] - a microwave generator is galvanically separated from the generated plasma;

[0037] - exactly one ionization zone and exactly one acceleration zone are provided, whereby these are arranged spatially and electrically consecutively and merge into one another; whereby when using

[0038] - a microwave field is formed or can be formed between the outer coaxial conductor potential and the inner coaxial conductor potential;

[0039] - the ionization zone is formed or can be formed near the inner coaxial conductor (3.1) or the central axis in the defined length interval [zc1, zc2];

[0040] - the acceleration zone is spatially formed between the anode and the cathode;

[0041] - in the ionization zone there is an axial static magnetic field generated by the permanent magnet stack and a radial high-frequency electric field generated by the microwave field with satisfied resonance condition between microwave and electron cyclotron frequency (ECR effect);

[0042] - the path under the influence of a magnetic field is structurally short for ions formed in the ionisation zone;

[0043] - the magnetic field of the permanent magnet stack is designed to run in the direction of the magnets after the end of the magnetic field effect, so that free electrons are spatially bound to the magnetic field and free ions are not or only slightly influenced by the magnetic field.

[0044] A permanent magnet stack can contain exactly four permanent magnets.

[0045] Preferably, the cathode can be designed as a grid or ring with high transparency. Transparency, as used herein, refers to the proportion of ions that do not collide with the mechanical structure of the grid or ring, but rather pass through it.

[0046] In particular, the microwaves can be in the range of 2.4 to 2.5 GHz and the magnetic field strength can have a value of 85.7 to 89.3 mT, so that the EZR effect is fulfilled.

[0047] In addition, the coaxial electrode arrangement can be designed to halve the length of the permanent magnet stack.

[0048] The permanent magnet stack can be made of ferrite.

[0049] Preferably, all connections of the generated plasma to the generator of the engine can be insulated by a ceramic and / or another dielectric.

[0050] The operating method according to the invention for operating the microwave cyclotron resonance plasma engine according to the invention, wherein during operation a thrust is generated by ions emerging from the engine, is characterized in that

[0051] - a static magnetic field with a field strength to fulfil the conditions of the EZR effect or to enable the EZR effect is present through the permanent magnet stack, with field lines of the magnetic flux density emerging at one end face of the permanent magnet stack and running back through the inner space enclosed by the permanent magnet stack to the other end face of the permanent magnet stack;

[0052] - a high-frequency alternating voltage with a frequency sufficient to generate a radial electric field between the inner coaxial conductor and the outer coaxial conductor is applied to satisfy the conditions of the EZR effect or to enable the EZR effect;

[0053] - an electrically neutral gas is fed into the microwave cyclotron resonance plasma engine via a gas inlet;

[0054] - the gas flows along the coaxial conductor;

[0055] - Plasma formation / ionization in the length interval [zc1, zc2] occurs due to the fulfilled resonance condition between microwave and electron cyclotron frequency (EZR effect);

[0056] - the formed plasma spreads towards the anode, whereby

[0057] - free electrons are withdrawn by the magnetic field which runs towards the magnets after the magnetic field action has ended and

[0058] - free ions pass through the anode, are electrostatically accelerated in the area between the anode and cathode and exit the system through the cathode.

[0059] The coaxial conductor can be insulated.

[0060] Furthermore, free electrons from the generation area can be reflected back into the ionization zone by the magnetic field running towards the end faces of the magnets.

[0061] The invention further relates to the use of the microwave cyclotron resonance plasma engine according to the invention and / or the operating method according to the invention in an engine or micro-engine or small engine for space travel. It can be used as a maneuvering engine in space travel, for example, for the repositioning and stabilization of satellites.

[0062] In general, semiconductor-based microwave plasmas are easy and efficient to generate, requiring little energy. Furthermore, microwave plasmas are particularly easy to start and control.

[0063] In particular, in a coaxial microwave discharge, the injected power is concentrated in a small volume, which is why very high ionization levels and power densities can be achieved, which leads to a high mass efficiency when used in an electric thruster in particular.

[0064] RIT (Radio Frequency Ion Thruster) and Kaufman ion sources require a much larger plasma-filled volume and suffer greater losses due to the interaction of the plasma with the walls.

[0065] With the inventive concept of the coaxial microwave setup, the ions are extracted from a small generation volume using relatively strong electric fields. Most of the plasma electrons are retained by the magnetic field.

[0066] Such propulsion systems are known and now in use. The basic principle is based on the ionization (plasma generation) of an electrically neutral propellant, followed by acceleration and ejection of the ions through an electrostatic field. The recoil accelerates the propulsion system and thus the body to which it is attached. Typical ion exit velocities are 10–100 km / s, which is one to two orders of magnitude higher than the velocities achievable by chemical combustion, so that even very small accelerated propellant masses generate a significant momentum, and the propellant mass is used very efficiently.

[0067] When using the microwave cyclotron resonance plasma thruster, functionality should be ensured at a power between 20 W and 300 W, although powers up to 1500 W are also possible. In contrast, when low thrusts are required (e.g., for attitude control), RIT, HEMPT, and Hall thrusters still require high power to generate the plasma.

[0068] The microwave cyclotron resonance plasma engine with plasma generation by the EZR effect in a permanent magnetic field has a combination of the following distinguishing features from the state of the art:

[0069] - the system is cylindrical and rotationally symmetrical;

[0070] - the ionization zone is located near the central axis in a defined length interval [zc1, zc2];

[0071] - in the ionization zone, a static axial magnetic field and a radial electric field with EZR frequency prevail;

[0072] - an electrostatic acceleration zone is arranged spatially separated from the ionization zone, whereby the distance between the two zones is small, so that the generated ions only have to travel a short distance under the influence of the magnetic field;

[0073] - the free electrons are guided by field lines reversing towards the magnets and, if necessary, reflected back into the ionization zone and

[0074] - the dynamic electric field is generated by a coaxial conductor with a protruding core, whereby the supplied neutral gas flows past the galvanically isolated coaxial conductor and unaffected by fields into the ionization zone.

[0075] It is a combination of an EZR microwave plasma source implementation using permanent magnets and accelerating electrodes, which makes it possible to realize an electric engine for use in space.

[0076] An advantage of the traveling wave tubes used to generate microwaves for grid ion engines in the previously mentioned Japanese Hayabusa mission was that the microwaves were used both for the main plasma and for the smaller plasma for neutralization, which represents a useful option for generating a microwave plasma, with the electrodes being designed to be potential-free with respect to satellites and each other.

[0077] This advantage can be similarly applied to a microwave cyclotron resonance plasma thruster, which is considered an advantage over alternative GIT concepts (HF or DC), which require separate power supplies for the neutralizers. The semiconductor technology used in this invention to create the thruster offers several advantages over traveling wave tubes, including lower mass, a robust and compact design, and straightforward impedance matching using variable frequency.

[0078] The invention is described below with reference to the enclosed figures in the figure description, which are intended to explain the invention and are not necessarily to be considered limiting:

[0079] They show:

[0080] Fig. 1 is a schematic representation of an embodiment of a microwave cyclotron resonance plasma engine according to the invention;

[0081] Fig. 2 shows an example of a test combination of a microwave plasma source with a permanent magnet stack;

[0082] Fig. 3 an exemplary photographic visualization of field lines in an outer tangential plane on a cylindrical permanent magnet stack with iron filings;

[0083] Fig. 4 shows an example of the simulation of the magnetic field from Fig. 3 using FEM simulation;

[0084] Fig. 5 is an exemplary representation of an experimental test setup for testing plasma generation in the arrangement shown in Fig. 2;

[0085] Fig. 6 is an exemplary representation of a section of the experimental test setup from Fig. 5 in which the light emission of the generated plasma can also be seen and

[0086] Fig. 7 shows an example of the extracted current as a function of the accelerating voltage at the plate electrodes and grids.

[0087] Fig. 1 shows a schematic representation of an embodiment of a microwave cyclotron resonance plasma (MCP) thruster 1 according to the invention. The MCP thruster 1 has a permanent magnet stack 2, an anode 4, a cathode 5, an insulating ceramic 3, and a coaxial electrode arrangement. The coaxial electrode arrangement comprises an inner coaxial conductor 3.1 and an outer coaxial conductor 3.2. A neutral gas, for example a noble gas, flows through the thruster via a gas inlet 7 and leaves it again via the cathode 5. The permanent magnets of the permanent magnet stack 2 all have the same direction of magnetization. The ceramic 6 electrically insulates all connections to the generator of the MCP thruster 1. For illustrative reasons, the generator is not part of the illustration.

[0088] The structure of MCP engine 1 is cylindrical, meaning it can be represented in the cylindrical coordinates R, z, <|), with the z-axis running vertically from bottom to top in the figure. In this example, rotational symmetry is assumed, i.e., independence from the azimuth angle <|). In principle, a non-rotationally symmetric cross-section is also possible. A cross-sectional deformation from a circle should not be ruled out.

[0089] The propellant is a neutral gas, which flows from the gas inlet at z=0 past a coaxial conductor in the positive z-direction. An alternating voltage of 2.45 GHz is applied to the coaxial conductor 3 between the inner coaxial conductor (core) 3.1 and the outer coaxial conductor (shield) 3.2. At z=zc1>0, the shield 3.2 ends, and the core 3.1 extends beyond the shield 3.2 up to z=zc2>zc1. A high-frequency electric field E of at least kV / m enters the gas-conducting space, predominantly in the interval [zc1, zc2]. The field near the core 3.1 exhibits only a radial component (R-direction). In the same interval, a permanent magnet stack 2 (i.e. an arrangement of ring-shaped permanent magnets) creates a static magnetic field which has only a z-component near the symmetry axis (z-axis, inner coaxial conductor 3.1).At a magnetic flux density of approximately 87.5 mT at 2.45 GHz, the conditions for electron cyclotron resonance are met in the vicinity of the exposed core 3.1, i.e., the free electrons can resonantly absorb energy from the electric field, and ionization occurs. Free electrons will then follow the magnetic field path and will be partially reflected in front of the end faces. The much heavier ions move beyond the interval [zc1, zc2] with little influence from the magnetic field. Finally, at z=zA, they pass through an annular anode 4 at a positive potential relative to the cathode 5, which forms the exit grid at z=zG, and are electrostatically accelerated in the interval [zA, zG]. The anode 4 is spatially arranged such that it does not extend into the coaxial conductor 3, as this would prevent the formation of the electric field E. The ions passing through cathode 5 provide the thrust for MCP engine 1.The cathode 5 has a high transparency and is preferably designed as a grid or ring.

[0090] The ionization zone [zc1, zc2] and the acceleration zone [zA, zG] are arranged spatially and electrically consecutively. The magnetic field is present in both zones, but in the acceleration zone, it acts as a confining force on the free electrons. At the ends of the cylinder, the magnetic field lines converge into the permanent magnet stacks 2. The higher flux density in front of the end faces can lead to a mirror effect, in which the electrons are reflected in the opposite direction and eventually return to the ionization interval. An increase in the free electron density there increases the energy absorption from the microwave field and promotes plasma generation.

[0091] The MCP engine 1 according to the invention is designed as a small engine, so that the permanent magnet rings of the permanent magnet stack 2 have an inner diameter of only a few centimeters.

[0092] Figure 2 shows an example of a test combination of a microwave plasma source with a permanent magnet stack 2. In the example shown in this figure, the permanent magnet stack 2 is formed from four ferrite permanent magnets. The microwave electrodes 9 are arranged bisecting the permanent magnet stack 2. The setup is vacuum-sealed. When operated with microwaves from 2.4 to 2.5 GHz, the EZR effect occurs throughout the entire inner, cylindrical, free area of ​​the setup.

[0093] Fig. 3 shows an exemplary photographic visualization of field lines 8 in an outer tangential plane on a cylindrical permanent magnet stack 2 with iron filings, wherein the plane touches the magnets at the line shown.

[0094] Fig. 4 shows an example of the simulation of the magnetic field from Fig. 3 using FEM (finite element) simulation.

[0095] Figures 3 and 4 clearly show that the magnetic field exhibits reversing field lines 8. Electrons are retained by these field lines 8, which converge in front of the front surfaces. The screen grid normally required in grid engines—the first of several grids arranged one behind the other—can be omitted, as the magnetic field with its reversing field lines 8 takes over its function. Only electrons are retained by the magnetic field. Ions have too large radii of gyration and are not deflected by the magnetic field.

[0096] Figure 5 shows an example of an experimental test setup for testing plasma generation in the arrangement shown in Figure 2. The permanent magnet stack 2 is formed of four ferrite permanent magnets with an inner diameter of 32 mm, an outer diameter of 72 mm, and a stack length of 60 mm. They form a homogeneous or nearly homogeneous internal field of 87 mT. Following the test combination of microwave electrodes 9 and permanent magnet stack 2 shown in Figure 2, a glass plasma expansion / extraction chamber 10 is connected to the magnets.

[0097] The elongated glass extraction chamber 10 serves to visualize the plasma 11 leaving the inventive structure. A grid 12 defines the glass body and is used to measure the current of the ions from the plasma 11. The ions are extracted from the plasma 11 by a bias voltage and measured as the current flowing through the perforated plate 12.

[0098] In addition, Fig. 6 shows an exemplary representation of a section of the experimental test setup from Fig. 5 during operation, in which the light emission of the generated plasma can also be seen.

[0099] Fig. 7 shows an exemplary representation of the extracted current measured with the test setup from Fig. 5 as a function of the accelerating voltage at the plate electrodes and grids 12. With an argon gas flow under vacuum conditions (p = 0.025 Pa) and a bias voltage of -120 V, an ion current of approximately 2.7 mA can be extracted.

[0100] List of reference symbols

[0101] 1 Microwave Cyclotron Resonance Plasma Engine (MCP Engine for short)

[0102] 2 permanent magnet stacks

[0103] 3 coaxial conductors

[0104] 3.1 Inner coaxial conductor / core

[0105] 3.2 Outer coaxial conductor / shield

[0106] 4 Anode

[0107] 5 Cathode

[0108] 6 Ceramics

[0109] 7 Gas inlet

[0110] 8 field lines

[0111] 9 microwave electrodes

[0112] 10 plasma expansion chamber / extraction chamber

[0113] 11 Plasma

[0114] 12 grids / perforated plate

Claims

Claims Microwave cyclotron resonance plasma drive (1) comprising a permanent magnet stack (2), a coaxial electrode arrangement, an anode (4) and a cathode (5), wherein - the permanent magnet stack (2) comprises at least one permanent magnet, wherein the at least one permanent magnet is ring-shaped and has a magnetization in the axial direction; - the coaxial electrode arrangement has an inner coaxial conductor (3.1) and an outer coaxial conductor (3.2); - the drive unit (1) is semiconductor-based and cylindrical, wherein the inner cross-sectional area is circular or elliptical or similarly circular; characterized in that - the permanent magnet stack (2) is arranged spatially extending in length beyond the coaxial electrode arrangement; - the inner coaxial conductor (3.1) is formed extending beyond the outer coaxial conductor (3.2) in a defined length interval [zc1, zc2]; - the cathode (5) has a high transparency; - the anode (4) does not extend spatially into the coaxial conductor (3) and is arranged downstream of the coaxial conductor (3) in the direction of flow; - all permanent magnets have the same magnetization direction in the axial direction; - a microwave generator is galvanically isolated from the generated plasma; - exactly one ionization zone and exactly one acceleration zone are provided, wherein these are arranged sequentially in space and electrical terms and merge into one another; wherein when using - a microwave field can be formed between the outer coaxial conductor potential and the inner coaxial conductor potential; - the ionization zone near the inner coaxial conductor (3.1) can be formed in the defined length interval [zc1, zc2]; - the acceleration zone is spatially formed between the anode (4) and the cathode (5); - in the ionization zone an axial static magnetic field generated by the permanent magnet stack (2) and a radial high-frequency electric field generated by the microwave field with a fulfilled resonance condition between microwave and electron cyclotron frequency are present; - the path under the influence of a magnetic field for ions formed in the ionization zone is structurally short; - the magnetic field of the permanent magnet stack (2) is configured to extend towards the magnets after the magnetic field effect has ended, such that free electrons are spatially bound to the magnetic field and free ions are not or only minimally affected by the magnetic field. Microwave cyclotron resonance plasma thruster (1) according to claim 1, characterized in that a permanent magnet stack (2) comprises exactly four permanent magnets. Microwave cyclotron resonance plasma thruster (1) according to claim 1 or 2, characterized in that the cathode (5) is configured as a grid or ring with high transparency. Microwave cyclotron resonance plasma thruster (1) according to any one of the preceding claims, characterized in that the microwaves are in the range of 2.4 to 2.5 GHz and the magnetic field strength has a value of 85.7 to 89.3 mT.Microwave cyclotron resonance plasma thruster (1) according to any one of the preceding claims, characterized in that the coaxial electrode arrangement bisects the permanent magnet stack (2) along its length. Microwave cyclotron resonance plasma thruster (1) according to any one of the preceding claims, characterized in that the permanent magnet stack (2) is made of ferrite. Microwave cyclotron resonance plasma thruster (1) according to any one of the preceding claims, characterized in that all connections of the generated plasma to the thruster's generator are insulated by a ceramic (6) and / or another dielectric.

8. Operating procedure for the microwave cyclotron resonance plasma drive (1) according to one of the preceding claims, wherein thrust is generated during operation by ions exiting the engine (1), characterized in that - a static magnetic field with a field strength sufficient to meet the conditions of the EZR effect is present through the permanent magnet stack (2), wherein field lines (8) of the magnetic flux density emerge at one end face of the permanent magnet stack (2) and return through the inner space enclosed by the permanent magnet stack (2) to the other end face of the permanent magnet stack (2); - an alternating voltage with a frequency is applied to generate a radial electric field between the inner coaxial conductor (3.1) and the outer coaxial conductor (3.2) to fulfill the conditions of the EZR effect; - an electrically neutral gas is supplied to the microwave cyclotron resonance plasma drive (1) via a gas inlet (7); - the gas flows along the coaxial conductor (3); - Plasma formation in the length interval [zc1, zc2] occurs due to the fulfilled resonance condition between microwave and electron cyclotron frequency; - the formed plasma spreads towards the anode (4), whereby - free electrons are retained by the magnetic field after the end of the magnetic field effect and - free ions pass through the anode (4), are electrostatically accelerated in the area between the anode (4) and cathode (5) and exit the system through the cathode (5).

9. Operating method according to claim 8, characterized in that free electrons from the generation area are reflected back into the ionization zone by the magnetic field extending towards the end faces of the magnets.

10. Use of the microwave cyclotron resonance plasma thruster according to any one of claims 1 to 7 and / or the operating method according to any one of claims 8 or 9 in a thruster or micro-thruster or small thruster for space travel.

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